Figure 6
(a) XPS survey spectrum of samples. The C 1s spectra can be seen in an inset. (b) UPS spectra of samples. Inverted black triangles indicate the feature attributable to non-hydrated areas of each sample. Features appearing at higher binding energies have been attributed to hydrated areas of samples. The secondary photoemission cut-off preceding these features has been used to determine the work function of the hydrated samples by linear extrapolation, as illustrated by dashed lines. The obtained work function values have been indicated under each spectrum. (c) High-energy-resolution XPS spectra of the Zn 2p3/2 core level measured in ZnO films of different thickness. The inset shows the Zn 2p3/2 peak position as a function of thickness. |